Α-Halonitroso COMPOUNDS. A REVIEW

Preparations ofC-Nitroso Compounds

“…The preferred method for the preparation of chloro- and bromo-nitroso compounds is the reaction of halogen or alkylhypohalite with oxime. This method, based upon the early work of Piloty and Schmidt, has been reviewed by Kosinski and Kresze et al and was employed by several groups in the 1950s. ,,− Diekman and Lüttke used tert- butylhypochlorite as the chlorinating agent for oximes (RR‘CNOH) to give geminal chloronitroso compounds in high yield (>90%) and purity (R/R‘ = H/Me, H/Ph, Me/Me, Me/ t -Bu, Me/ n -Bu, Me/CH 2 Ph, and (CH 2 ) 5 ). The same reagent was used to oxidize five para -substituted phenylhydroxylamines to their nitroso derivatives .…”

Product Class 5: Hydroxylamines

“…[139] Scheme 34 Synthesis of N-(Aminoalkyl)hydroxylamines [139] 48−67% The disadvantage of hydroxylamines of type 111 is that they are susceptible to oxidation and disproportionation, but this is not observed for products derived from electron-deficient a-chloro-a-nitroso compounds. [143][144][145][146][147][148][149][150][151] For example, reaction of 2-chloro-2-nitrosoadamantane (112) with isopropenylbenzene gives, by hydrochloride elimination from transient 113, the nitrone hydrochloride 114, which upon hydrolysis provides the respective N-(2-phenylallyl)hydroxylamine hydrochloride (115) along with adamantan-2-one (116) (Scheme 36). [143] Scheme 36 Synthesis of N-(2-Phenylallyl)hydroxylamine [143] rt, 10 d 1-Chloro-1-nitrosocyclohexane is a convenient reagent for the asymmetric synthesis of a-(hydroxyamino) acids 120.…”

“…[144,145] Thus, successive treatment of N-acylsultams of type 117 with sodium hexamethyldisilazanide and then 1-chloro-1-nitrosocyclohexane, followed by acidic hydrolysis of the intermediate nitrone 118, produces diastereomerically pure N-hydroxyamino acid derivatives 119, which are finally converted into the target a-(hydroxyamino) acids 120 (Scheme 37). [145] Scheme 37 Asymmetric Synthesis of a-(Hydroxyamino) Acids [145] Enhanced reactivity for the ene reaction is observed for 1-chloro-1-nitroso carbohydrates of type 121-123, [146][147][148][149][150] owing to the inductive electron pull by the adjacent ether function. [151] A series of several N-allylic substituted hydroxylamines 126 are obtained from reaction of 121 with different alkenes 124 via the nitrones 125 (Scheme 38).…”

Synthesis of α-Functionalized and Nonfunctionalized Hydroximoyl Chlorides from Conjugated Nitroalkenes and Nitroalkanes

“…The latter gives α-halonitroso derivative D via C by loss of TiOCl 2 and chloride transfer. Intermediate D then isomerizes to hydroximoyl chloride 2 (Scheme ).

2

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